Selectivity of ion exchangers in extracting cesium and rubidium from alkaline solutions

We compare the ion exchange selectivity of phenol-type sorbents based on phenol formaldehyde resins, products of condensation of diatomic phenols with formaldehyde, and crosslinked polymer based on C-phenyl[4]resorcinarene resin, for cesium and rubidium ions. It is shown that phenol formaldehyde sorbents are the ones most selective. The interaction of alkali metal cations with the anion of calix[4]arene is investigated via quantum-chemical modeling. It is shown that the selectivity toward cesium and rubidium ions in ion exchangers of the phenolic type is not due to specific interactions of ions with phenolic groups.